Explain removal of nitrogen in deamination
Follow the nitrogen-containing part without converting the whole amino acid directly into urea.
Exam scope and assessment notes
Extended only (Supplement) · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Recall cell metabolism, blood transport, amino acids and the distinction between excretion and egestion.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What is removed during deamination?
What you will learn
- Deamination separates the nitrogen-containing part
- The liver forms urea for excretion
Explain removal of nitrogen in deamination
| Feature | Meaning |
|---|---|
| Deamination | Removal of nitrogen-containing part |
| Nitrogen pathway | Liver processing → urea |
| Remainder | Separate metabolic fate |
| Next route | Urea in blood → kidneys |
Deamination separates the nitrogen-containing part
Deamination is removal of the nitrogen-containing part of amino acids in the liver’s handling of an excess. The removed nitrogen is processed into urea, which blood can carry to the kidneys for excretion. This links a chemical change with the waste-removal route rather than defining deamination as a kidney filtration event.
Use the required nitrogen-containing wording. Removing every carbon atom or simply moving an amino acid through a ureter does not describe deamination. The remainder of the amino-acid molecule has a separate fate in metabolism; it is not correct to label every atom of the entire starting molecule as the same urea product.
The liver forms urea for excretion
For this course, the process is an outline and detailed intermediate reactions are not required. The liver processes the nitrogen released from excess amino acids into urea; the simplified arrow is not a balanced chemical equation or a claim that the removed part itself is already a urea molecule. This distinction preserves the required account without inventing a single-step universal mechanism.
Assimilation builds useful proteins from amino acids; deamination processes an excess and leads to nitrogenous waste formation. Both can be liver roles, but their starting context and material destination differ. The kidneys then excrete urea, while ureters, bladder and urethra transport, store and release the urine rather than performing the nitrogen-removal reaction.
Pause and explain
Which explanation fits the syllabus outline?
Worked example
Describe deamination at the required outline level.
Show the worked solution
- Remove the nitrogen-containing part of amino acids.
- Connect its liver processing with urea formation.
Answer Deamination removes the nitrogen-containing part of excess amino acids; the liver processes the nitrogen into urea.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Define deamination and connect it with urea formation.
Give me a hint
Name the removed part and liver product.
Compare my reasoning
- Nitrogen-containing parts are removed from excess amino acids.
- The liver processes that nitrogen into urea.
Deamination removes the nitrogen-containing part of amino acids; liver processing of the released nitrogen forms urea for excretion.
Look for these in your work
- Use nitrogen-containing part
- Connect with liver urea formation
Correct: deamination is filtration of intact amino acids through the bladder.
Give me a hint
A chemical change differs from fluid movement.
Compare my reasoning
- Deamination removes the nitrogen-containing part in liver processing.
- Bladder stores urine rather than filtering intact amino acids.
Deamination is a liver chemical-processing step removing the nitrogen-containing part of amino acids; it is not filtration through the urinary bladder.
Look for these in your work
- Distinguish chemistry and movement
- Correct the organ role
Why should a simplified excess amino acid → urea arrow not be read as a complete one-step balanced equation?
Give me a hint
A flow summary omits detailed reactions and other molecular fates.
Compare my reasoning
- Only the nitrogen-removal and waste route are outlined.
- Other parts and intermediate reactions are not specified.
It summarises removal and processing of nitrogen, not conversion of every starting atom into urea in one step; detailed intermediate reactions are outside the required outline.
Look for these in your work
- Identify the schematic limit
- Avoid whole-molecule conversion
Common mistakes
- Calling nitrogen removal filtration.
- Turning every atom of an amino acid into urea.
What can you explain now?
Which explanation fits the syllabus outline?
Compare with the explanation
Removed amino-acid nitrogen is processed into urea in the liver
It links deamination and waste formation.
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Make it stick
Define deamination with the removed part and correct formation site.
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